In my near-coastal California garden (USDA Zone 9b or 10a), I've had some success with Clematis. They do best in Full Sun, at least half a day, and should be planted in rich, well-draining soil and receive regular irrigation from Spring through Fall.
The only places in California rated USDA Zone 6b occur at fairly high elevation in the mountains or on the Modoc Plateau.
I presume the OP's garden is in the Sierra Nevada above the Central Valley.